Sheet stacking apparatus



Nov. 11 1969 H. OSBORN 3,477,323

SHEET STA CKING APPARATUS Filed March 15, 1967 6 Sheets-Sheet 1 Inventor U h, /as HOVARI 580!? I Allo'rney,

Nov. 11, 1969 H. OSBORN 3,477,323

SHEET STACKING APPARATUS Filed March 15, 1967 6 Sheets-Sheet 2 I nvenlor HOWARD OSBORN B y 0 Attorneys Nov. 11, 1969 H. OSBORN ,477,

SHEET STACKING APPARATUS Filed March 13, 1967 6 Sheets-Sheet 3 I noenlor now" D 05808 N itorney I Nov. 11, 1969 H. OSBORN 3,477,323

SEEET STACKING APPARATUS Filed March 13, 1967 6 Sheets-Sheet 4 Inventor flown! 08803 N QM n A ttorneyg Nov. 11, 1969 H. OSBORN I 3,477,323

SHEET STACKING APPARATUS Filed March 15, 1967 6 Sheets-Sheet 5 In venlor H WARD 0586 RM Attorne y 3.

Nov. 11, 1969 OSBORN 3,477,323

SHEET STACKING APPARATUS Filed March is, 1967 s Sheets-Sheet a In venlar HOWARD 0850K N Attorney United States Patent 3,477,323 SHEET STACKING APPARATUS Howard Osborn, Aylesbury, England, assignor to Wiggins Teape Research & Development Limited, London, England, a British company Filed Mar. 13, 1967, Ser. No. 622,504 Claiins priority, application Great Britain, Mar. 18, 1966, 12,034/ 66 Int. Cl. B26d /28, 7/06 US. CI. 83-79 20 Claims ABSTRACT OF THE DISCLOSURE Sheets being delivered to form a stack on a support are moved towards a stop at a high linear speed and before the leading edge of a sheet engages the stop the trailing end portion of the sheet is engaged by a selectively operable retarding device which reduces considerably the linear speed of the sheet and continues the movement of the sheet at the lower speed until the leading edge of the sheet engages the stop.

BACKGROUND OF THE INVENTION Field of the invention Description of the prior art Many forms of apparatus are known for stacking sheets and while it is at present accepted that the economic speed for cutting and slitting webs of paper is of the order above mentioned at such speeds difiiculties arise in regard to the collection and stacking of the cut sheets, particularly if the sheets are of lightweight paper, because if collection and stacking is effected at linear speeds in excess of 150 to 200 feet per minute there is a tendency for the sheets to be damaged by creasing or folding, and to overshoot the collecting and stacking position. It is clear, therefore, that to reduce or avoid these disadvantages the linear speed of the sheets during collection and stacking must be retarded and this is usually effected either by arranging for overlapping of the sheets, or by the use of a collating drum. If the sheets are overlapped they form an uneven stack and although with heavyweight paper the sheets may be jogged-up to form a neatly aligned stack, jogging is diflicult to achieve with lightweight papers. On the other hand it is found that the use of collating drums is unsatisfactory for some kinds of paper, particularly lightweight papers, of the carbonless copying kind where any excess pressure on the sheets causes permanent marking of the sheets.

It is a main object of the present invention to provide a sheet stacking apparatus which avoids the difficulties and disadvantages mentioned above and which can be used to stack either lightweight or heavier-weight sheets.

SUMMARY According to the invention there is provided sheet stacking apparatus in which sheets are moved in succession towards a stop associated with a support on which the sheets are to be superimposed with the leading edges thereof abutting the stop, wherein each sheet is initially engaged and moved over the support at a high linear speed 3,477,323 Patented Nov. 11, 1969 Brief description of the drawings FIG. 1 is a diagrammatic illustration of apparatus according to the invention, and

FIG. 2 is a section through a suction box embodied in the apparatus, and with reference to the accompanying drawings in which:

FIG. 3 is a diagrammatic illustration of a modified form of the apparatus shown in FIG. 1,

FIG. 4 is a section through a presser pad embodied in the apparatus of FIG. 3,

FIG. 5 is a diagrammatic illustration of a mechanical control apparatus which can be substituted for the electrical control apparatus shown in FIGS. 1 and 3,

FIG. 6 is a section through a suction box embodied in the apparatus of FIG. 5,

FIG. 7 is a section through a presser pad embodied in the apparatus of FIG. 5,

FIG. 8 is a diagrammatic side view of a further modified form of the apparatus, and

IG. 9 is a view in the direction of arrow IX, FIG. 8.

In the drawings like reference numerals refer to like or similar parts.

Description of the preferred embodiments Referring to FIGS. 1 and 2 of the drawings, a web 1 of paper is fed to a cutting device 2 and sheets 3 cut from the web are delivered to continuously moving endless belts 4, 5 which pass respectively round rollers 6, 7 and 8, 9 and feed the sheets towards a stacking device at a high linear speed, that is a speed greater than that at which cutting is effected, the said high linear speed being about 800 feet per minute, so that gaps are formed between the successive sheets.

The stacking apparatus includes a stop 10 associated with a support 11 on which the sheets are to be superimposed With the leading edges thereof abutting the stop 10. Each sheet 3 as it leaves the belts 4, 5 is initially engaged on one side thereof 'by a first endless band conveyor 12 and is moved over the support 11 at the high linear speed at which it is moved by the belts 4, 5. Before the leading edge of the sheet engages the stop 10, however, the trailing end portion of the opposite side of the sheet opposite that engaged by conveyor 12 is engaged by a second endless band conveyor 14 which reduces considerably, that is to between and 200 feet per minute, the linear speed of the sheet as compared with the high linear speed at which it is first moved over the support and which continues the movement of the sheet until the leading edge thereof engages the stop 10.

The endless band conveyor 12 may be a perforated continuously movable endless band, or side-by-side tapes, the sheet-engaging run of which cooperates with a first suction box 13. The second conveyor means comprises a second perforated continuously mova'ble endless band or tape 14 having a straight sheet-engaging run is movable towards the support 11, which co-operates with a suction box 15 to engage the trailing end portion of a sheet, and which vis spaced from the sheet-engaging run of the band 12 a part of which extends over said straight run portion of band 14, The selective operation of the second conveyor means 14 is effected by a control device which, in the embodiment shown in FIG. 1, is arranged to sense the passage of a sheet 3 towards the first perforated endless band 12 and to effect operation of va ves 16, 17, associated respectively with the suction boxes 13,

15, in a manner such that as one suction box is rendered effective the other is rendered ineffective. The sheet-engaging run of the band or tape 14 is spaced from the sheetengaging run of band 12 to ensure that when the suction box 13 is rendered ineffective and the suction box 15 is rendered effective the sheet is drawn into engagement with band 14 and does not tend to adhere to band 12 due to any residual effect from suction box 13. The spacing between the sheet-engaging run of band 14 and that of band 12 also permits the leading end of the next on-coming sheet, which is moving at high speed, to pass over the trailing end of the slower moving sheet being moved by band 14.

The control device as diagrammatically illustrated in the drawing comprises a photo-electric cell 18 operable to sense the tail or trailing end of each sheet and to pass a signal to a first differentiator and limiter 19 which in turn feeds a signal to a delay generator 20 arranged to determine the time at which suction will be applied by suction box 15 to the trailing end portion, that is at a position about 1 /2 to 6 inches from the trailing edge of a sheet 3 being moved by the band 12. A signal is fed from generator 20 to a second differentiator and limiter 21 which in turn feeds a signal to a solenoid drive 22 which sends signals which respectively control the operation of the valves 16, 17.

The valve 17 is located in a recess 23, FIG. 2, covered by a perforated seating plate 24, and is operated by a pair of solenoids 25, 26. A signal from the solenoid drive 22 is transmitted to solenoid 25 which operates a cam mechanism 27 to raise the valve 17 for the selected time after which the signal is transferred to solenoid 26 which operates the cam mechanism in the opposite direction to pull the valve 17 back on to the seating plate 24.

The solenoid drive sends a first signal to solenoids which open valve 17 and close valve 16. The suction head applied to suction box 15 is of the order of 11 pounds per square inch and is greater than that applied to suction box 13 and which is only about two pounds per square inch. Accordingly when suction is applied to box 15 the trailing end portion of the sheet is drawn away from band 12 and into engagement with band 14. This causes the linear speed of the sheet to be retarded to about 150 feet per minute, and due to the suction effect between the sheet and band 14 the sheet continues to be advanced until the leading edge abuts the stop 10 by which time the trailing end of the sheet has passed the suction box 15 and the sheet is disengaged and falls on to the support 11 or on to a sheet already delivered thereto. At this time the solenoid drive sends a second signal which closes the valve 17 and opens valve 16.

The support 11 and the sheet-engaging runs of the endless bands 12, 14 are inclined downwards towards the stop 10 at an angle of between to 50.

As indicated in broken lines in the drawing, the support may be lowered or rocked from the sheet collecting position thereof, for example when a ream of sheets has been delivered thereto, so that the pile or stack of sheets may be removed for packaging. While this is being done succeeding sheets may be diverted on to a second support 11a by a deflector 128. When the apparatus is to operate thus, two belts are provided, as illustrated in FIG, 1, and the other of the belts 5 delivers the sheets on to the support 11a which is associated with sheet retarding devices as described above and which are indicated by like reference numerals suffixed by the letter a. It will be understood that if it is not desired at times to deflect sheets on to a second support only one belt 5 need be provided.

When, as stated above, a sheet consists of a batch of superimposed lightweight sheets the batches are cut by the cutting device 2 from superimposed webs and the suction boxes 13 and 13a can be omitted because the effect of the suction action of the suction boxes 15, 15a does not pull all of the sheets cleanly off the bands 12, 12a and suction boxes 13, 13a and the leading edges of oncoming sheets will not pass over the trailing ends of the slower moving sheets without sometimes colliding with them. The effect of the suction pulse from the suction box 15, or a, does however diminish through the batch and it may in some instances be found that the upper sheets of a batch may tend to slip relative to the lower sheets when the batch is retarded. To overcome this tendency the apparatus is provided with a reciprocable pad 28, FIGS. 3 and 4, which is located over the suction box 15. The sheets moving at high speed pass between the sheet-engaging run of band 14 and the underside of pad 28 which is constituted by a perforate or air pervious wall 29 forming the bottom of a chamber 30. The wall 29 may be provided with discrete holes 31 or it may be made of a porous material such as sintered metal, plastics, or ceramic. The chamber is airtight except for the air pervious wall 29 and pressurised air, at a pressure of about 5 to 70 p.s.i. is admitted to the chamber 30 through a pipe 32 from any suitable source such as a pump 33. The air delivered to the chamber 30 bleeds out of the chamber through the Wall 29 and forms an air cushion between the pad 28 and a sheet passing between the pad and the sheet-engaging run of the band 14 to prevent the pad from marking or damaging the sheet. If desired, instead of the bottom wall 29 being air pervious and cooperating with a chamber 30 the pad may be a solid member provided on the underside thereof with a soft material, such as rubber, which will serve the same purpose as that of the air cushion.

The pad 28 is reciprocated by a cam mechanism 27a which is operated by a pair of solenoids 25a, 26a which operate in conjunction with the solenoids 25, 26 in a manner such that when solenoid 26 is activated to open volve 17 the solenoid 26a is caused to move the pad 28 downwards to hold the sheet against the band 14. Similarly, when solenoid 25 is activated to close valve 17 the solenoid 25a causes the pad 28 to be raised.

In the foregoing, the valves 16, 17 and the valve 17 and pad 28 have been described as being selectively operated by an electrical control device. It is, however, to be understood that other forms of control device may be used and FIGS. 5 to 7 diagrammatically illustrate a mechanical control device in which a belt 34 or the like is driven from the shaft 35 for the lower cutter element 2 and drives the input shaft 36 of a differential gear 37 the output shaft 38 of which, through a belt 39 or the like, rotates a cam 27b and, through a belt 40 or the like, a cam 27a. The ratio of the drive between shaft 35 and cams 27b, 27c is arranged to be 1:1. This ensures that the cam 27b which controls operation of suction box 15 always operates in conjunction with pad 28 as described above.

The purpose of the differential gear 37 is to alter the phase relationship of the input and output shafts 36, 38 to accommodate different sheet lengths, variation of which requires that the suction pulse be advanced or retarded so that it always acts on the rear or trailing end of a sheet.

A separate differential gear 37 will normally be necessary for each layboy because the length of the path between the cutter device and the suction box 15 will vary. The phase between the input shaft 36 and the output shaft 38 is altered by rotation of the differential housing 41 which rotates the input and output shafts relative one to the other.

It will be understood that, if desired, forms of differential, for example a flange coupling with slotted holes, alternative to that described above may be used.

The mechanically operated valve 17 and pad 28 are respectively illustrated in FIGS. 6 and 7 and from FIG. 6 it will be seen that the valve 17 differs from that shown in FIG. 2 in that the cam 27 is replaced by a cam 27b and the valve is retained in the closed position thereof by a spring 42. The pad 28, FIG. 7, is urged to the upper position thereof by a spring 43.

During each revolution of the cutting device 2 a sheet is cut from the web and cam 27b is rotated once. Thus the valve 17 is opened, and the pad 28 is lowered in timed relation with the opening valve 17, once for each sheet.

When the suction box 13 is dispensed with it is sometimes found, if the sheets are of light weight, that there is some difiiculty in causing an on-coming sheet moving at high speed to move over the top of the sheets already on the support 11. To overcome this difilculty the sheets are stiffened longitudinally by upturning the edge portions thereof as illustrated in FIG. 9. This is effected by plough type folder elements 44, FIGS. 8 and 9, which engage beneath the opposite longitudinal edge portions, FIG. 9, of the sheet and turn the edge portions upwards as shown at 45 in FIG. 9. The plough elements 44 extend from the front end of the suction box 15, see FIG. 8, to the stop 10 and to ease the entry of the sheet into the plough elements 44, which are of constant cross-section, auxiliary fixed plough elements 46, FIG. 8, are positioned just in front of the plough elements 44. By reason of the provision of the plough elements 44, a sheet can travel at high speed over the sheets already on the support 11, being driven by the belts 4, 5. However, if the plough elements 44 were fixed ploughs a sheet being moved to the support would collide with sheets already at this position and a sheet engaged by the plough elements 44 would not be delivered to the pile on the support 11 because its edge portions would be held by the plough elements. For this reason the plough elements 44 are rotatable intermittently, in directions indicated by arrows A, FIG. 9. This causes the edge portions of a sheet, on initiation of the suction pulse from suction box 15, to be disengaged from a sheet so that the sheet falls freely on to the top of the pile on the support 11 and the next pair of plough elements is moved into position to receive the next succeeding sheet.

As shown in FIG. 9, the plough elements 44 are turned through 90 during each rotational movement thereof and rotation is effected in timed relation with the operation of the cutting device 2. As shown in FIGS. 8 and 9 the ploughs are combined with mechanical control apparatus as described with reference to FIGS. 5 to 7 but it is to be understood that the plough elements could be rotated by electrical control apparatus.

Referring to FIGS. 8 and 9, a chain 47, FIG. 8, or the like is driven from the shaft for cam 27b, FIG. 5, and drives a sprocket 48 on a shaft 49 which also carries a bevel gear wheel 50 which meshes with another bevel gear wheel 51. The gear ratio between the shaft for cam 27b and bevel gear wheel 51 is 1:1 so that the gear wheel 51 rotates once for each revolution of the cutting device 2. The bevel gear wheel 51 carries a crank-pin 52, FIG. 8, which is coupled to one end of a link 53 the opposite end of which is connected to one end of an arm 54 mounted on one side of the plough assembly. The other end of arm 54 is connected by a link 55 to a second arm 56 mounted on the other side of the plough assembly. Each rotation of gear wheel 51 causes rotation of the plough elements 44 through 90, the oscillatory movement of arms 54, 56 being converted into rotary movement in one direction by a ratchet device mounted on the plough shaft 57. It will be understood that any suitable form of ratchet device may be used but as illustrated in FIG. 8 the ratchet devices consist of bodies 58 to which the arms 54, 56 are secured, the bodies 58 being freely rotatable about the plough shafts 57. Mounted on shafts 57 are further bodies 59 and the bodies 58, 59 are provided with matching serrations 60, FIG. 8. The serrations 60 are so designed that the bodies 58 will drive the bodies 59 in one direction only, as indicated by the arrows 46, FIG. 9. If a body 58 is moved in an opposite direction to that of its driving direction the co-operating body 59 can slip against it by moving axially along shaft 57 against a spring 61, FIG. 8. Each body 59 has a pin, not shown, engaging in a slot 62 in its shaft 57 so that the body 59 can move axially along the shaft but cannot rotate around the shaft.

The phase relationship of bevel gear wheel 50 to the shaft for cam 27b is so arranged that the plough elements 44 are moved to release a sheet as the suction pulse from 'box 15 commences.

In FIG. 9 the plough devices each 'have four equispaced plough elements 44 but it will be understood that each device may have a number of plough elements greater or less than four but not usually more than eight. Each device will of course have the same number of plough elements. Further, mechanisms other than that described above can be used to drive the plough devices, for example cam or Geneva mechanisms may be used.

I claim:

1. Sheet stacking apparatus comprising a support on which the sheets are to be superimposed a stop associated with the support and against which the leading edges of superimposed sheets abut, first conveyor means operable to receive sheets moving towards the support and to move the sheets in succession over the support towards the stop perforate second conveyor means movable at a linear speed less than that of the first conveyor means and including a straight run portion movable towards the support and engageable by the trailing end portions of the sheets, a suction box associated with said straight run portion to draw the trailing end portion of a sheet into engagement with the straight run portion to permit movement of the sheet thereby against the stop, and a control device operable to render the suction box inefie-ctive except when the trailing end portion of a sheet overlies said straight run portion of the second conveyor means.

2. Apparatus according to claim 1, wherein the first conveyor means comprises a continuously movable perforated endless band the sheet-engaging run of which at least in part extends over the straight run portion of the second conveyor means and co-operates with a suction box associated therewith, and wherein the control device effects operation of valves associated with said suction boxes in a manner such that as one suction box is rendered effective the other is rendered ineffective.

3. Apparatus according to claim 2, wherein the suction effect of the suction box associated with the second conveyor means is greater than that of the suction box associated with the first conveyor means.

4. Apparatus according to claim 1, wherein the control device effects operation of a valve associated with the suction box thereby to apply a suction pulse to the trailing end portion of a sheet passing over the straight run portion of the second conveyor means.

5. Apparatus according to claim 4, including a pad reciprocable towards and away from said straight run portion and operable by the control device to press a sheet against the straight run portion as a suction pulse is terminated.

6. Apparatus according to claim 5, wherein the underside of the pad which presses the sheet against the straight run portion is cushioned to avoid damage to the sheet.

7. Apparatus according to claim 6, wherein the cushion is formed by a layer of pressurised air emitted through the underside of the pad from an air-receiving chamber formed in the pad.

8. Apparatus according to claim 5, wherein the valve and the pad are operated by solenoids, operation of which is controlled through a timing device by a sensing device arranged to sense the trailing end of a sheet leaving a cutting device by which the sheet is cut from a web.

9. Apparatus according to claim 7, wherein the valve and the pad are operated by solenoids, operation of which is controlled through a timing device by a sensing device arranged to sense the trailing end of a sheet leaving a cutting device by which the sheet is cut from a web.

10. Apparatus according to claim wherein the sheet is cut from a web by a rotatable cutting device, the valve and the pad are operated by cams appropriate thereto, and the cams are rotated in synchronism with the cutting device through a differential gear.

11. Apparatus according to claim 7, wherein the sheet is cut from a web by a rotatable cutting device, the valve and the pad are operated by cams appropriate thereto, and the cams are rotated in synchronism with the cutting device through a differential gear.

12. Apparatus according to claim 4, including plough type folder elements movable into and out of the path of opposite longitudinal edge portions of a sheet advancing into position over said band, said plough type folder elements being operable to turn said edge portions up wards to effect stiffening of the sheet and to be disengaged from the sheet on initiation of the suction pulse.

13. Apparatus according to claim 12, including auxiliary plough type folder elements fixedly mounted in advance of said movable plough type folder elements and arranged to initiate the upturning of said edge portions of the sheet.

14. Apparatus according to claim 10, wherein plough type folder elements are movable into and out of the path of opposite longitudinal edge portions of a sheet advancing into position over said band, wherein the plough type folder elements are operable to turn said edge portions upwards to effect stiffening of the sheet and to be disengaged from the sheet on initiation of the suction pulse, and wherein the movable plough type folder elements are supported for intermittent rotation about axes extending lengthwise of the path of the sheet, and driving means operable in synchronism with the cutting device the valve, and the pad are arranged to effect rotation of the plough type folder elements about said axes.

15. Apparatus according to claim 14, wherein at least two equi-spaced plough type folder elements are rotatable about each said axis and for each rotation of the cutting device the driving means rotates the plough type folder elements through an angle of 360 divided by the number of plough type folder elements.

16. Apparatus according to claim 7, wherein the sheet is cut from a web by a rotatable cutting device, the valve and the pad are operated by cams appropriate thereto, and the cams are rotated in synchronism with the cutting device through a differential gear.

17. Apparatus according to claim 16, wherein plough type folder elements are movable into and out of the path of opposite longitudinal edge portions of a sheet advancing into position over said band, wherein the plough type folder elements are operable to turn said edge portions upwards to effect stiffening of the sheet and to be disengaged from the sheet on initiation of the suction pulse, and wherein the movable plough type folder elements are supported for intermittent rotation about axes extending lengthwise of the path of the sheet, and driving means operable in synchronism with the cutting device, the valve, and the pad are arranged to effect rotation of the plough type folder elements about said axes.

18. Apparatus according to claim 17, wherein at least two equi-spaced plough type folder elements are rotatable about each said axis and for each rotation of the cutting device the driving means rotates the plough type folder elements through an angle of 360 divided by the number of plough type folder elements.

19. Apparatus according to claim 2, wherein the support and the straight run portion of the second conveyor means, and when appropriate the sheet-engaging run of said continuously movable endless band, are inclined downwards towards the stop at an angle of between 0 and 50 with the horizontal.

20. Sheet stacking apparatus comprising, in combination,

a support for receiving stacked sheets,

high speed conveyor means for moving successive sheets toward said support at high linear speed and having a terminal portion disposed on one side of the sheets, retarding conveyor means disposed in spaced opposed relation to said terminal portion of the high speed conveyor means and on the opposite side of the sheets for moving successive sheets toward said support at a linear speed substantially less than said high linear speed, first means for holding successive sheets against said terminal portion of said high speed conveyor means out of contact with said retarding conveyor means,

second means for holding successive sheets against said retarding conveyor means out of contact with said high speed conveyor means,

and means for alternately actuating said first and second means as each sheet passes through the region between said terminal portion of the high speed conveyor means and said retarding conveyor means.

References Cited UNITED STATES PATENTS 2,381,719 8/1945 Brintnall 27168 2,427,223 9/1947 Moore 27168 X 3,178,174 4/1965 Schneider 271-74 X 3,232,605 2/1966 Plummer et a1. 27146 3,336,028 8/1967 Schonmeir 27146 X JAMES M. MEISTER, Primary Examiner US. Cl. X.R. 

